1. Field of the Invention
The present invention relates to facsimile apparatuses that communicate over telephone public line networks and IP networks, control methods thereof, and storage medium.
2. Description of the Related Art
Recent years have seen the spread of communication terminal apparatuses connected to telephone public line networks such as Public Switched Telephone Networks (PSTN) as well as IP networks. Next Generation Networks (NGN) aimed at providing telephone and video communication services (called “public IP networks” hereinafter) have also begun to appear. Accordingly, communication terminal apparatuses that run on such NGNs are becoming more common. However, as shown in FIG. 2A, in the case where a plurality of networks are present in a given environment, users are unable to know what communication mode a given partner can be called through. Thus a technique is known in which an administrator creates a communication mode registration list, which associates prefixes of destination numbers with communication modes, in advance; when a user then inputs a partner telephone number, that number is compared with the registration list and the partner is called through the matching communication mode.
However, there are cases where communication errors occur even when this technique is employed. For example, the partner communication terminal may be an analog fax apparatus capable only of communication over a telephone public line network. In such a case, when a call is made over an IP network and a resulting communication error is detected, it is necessary to fall back on the telephone public line network. With the communication terminal apparatus disclosed in Japanese Patent Laid-Open No. 2012-134883, for example, a user may wish to communicate with an analog fax apparatus 207, but may be unaware that the partner device is an analog fax communication apparatus and may thus call the partner device through a public IP network, as illustrated in FIG. 2B. In this case, the communication terminal apparatus detects a communication error from a home gateway (HGW) and analyzes whether the detected communication error is an error requiring falling back on a telephone public line network or if the error does not require falling back. It is furthermore automatically determined whether to re-call over the IP network or re-call over the telephone public line network based on a result of the communication error analysis and a setting, made in the device in advance, for whether or not to execute fall-back processing for re-calling over the telephone public line network.
However, this conventional technique poses the following problem. The communication terminal apparatus in the above conventional technique will incur lower communication costs and will experience higher communication speeds when communicating over an IP network than when communicating over the telephone public line network, and thus users may prefer to avoid communicating over the telephone public line network. For example, a user may execute a transmission task having selected a communication mode in which the call is made over an IP network. However, in the case where a communication error occurs and a fall-back setting for re-calling over the telephone public line network is active as described above, there is a problem in that the re-call will be made over the telephone public line network in spite of the user's intent and desire to communicate over the IP network.